Balancing supply and demand of electrical energy over time and location is a longstanding problem in an array of applications from commercial generator to consumer. The supply-demand mismatch causes systemic strain that reduces the dependability of the supply, inconveniencing consumers and causing loss of revenue. Since most electrical energy generation in the United States relies on the combustion of fossil fuels, suboptimal management of electrical energy also contributes to excessive emissions of pollutants and greenhouse gases. Renewable energy sources like wind and solar power may also be out of sync with demand since they are active only intermittently. This mismatch limits the scale of their deployment. Large-scale energy storage may be used to support commercial electrical energy management by mitigating supply-demand mismatch for both conventional and renewable power sources.
Electrochemistry-based technologies offer viable solutions for the storage of energy in an uninterruptible power supply environment. Many types of electrochemical cells have been used for large-scale energy storage. These cells provide efficient storage capabilities because of the rapid ionic migration and fast, reversible kinetics at both metal electrodes. Energy is stored at the negative electrode which is constituted mainly of a metal, referred to herein as the active metal or anodic metal, having a high chemical potential. In a discharged state, the active metal resides in the positive electrode at a low chemical potential in the form of an alloy. An electrolyte disposed between two electrodes enables ionic transportation of the active metal during charging or discharging. For example, descriptions of such cells may be found in U.S. Pat. No. 8,323,816, US Patent Publication No. US-2011-0014505-A1 and US Patent Publication No. US-2012-0104990-A1, the entire contents of which are incorporated herein by reference.
It is known in the art that batteries with solid phase electrodes typically demonstrate limited cycle life because of volume changes during charge/discharge cycling that leads to mechanical degradation. In contrast, batteries using liquid phase electrodes can lead to prolonged lifetime by intrinsically overcoming mechanical degradations. However, liquid phase regions must often be constrained to a small composition range, which in turn, limits the electrode's utilization and increases cost.